George keith



e. KEITH AND 1. E. 'E OINTON.- SAFETY CUT-OUT DEVICE FOR USE ON GAS SUPPLY SYSTEMS.

' APPLICATION FILED SEP'HW 192],

1,427, 82 1. Patented Sept. ,5, 1922.

Patented Sept 5, 1922.

UNITED stares rarest orrica.

GEORGE KEITH, OF LONDON, ENGLAND, ANID JOHN Elli/YARD POINTON, OF PETER- BOBOUGH, ENGLAND, ASSIGNORS TO JAMIES KEITH & BLAGKIXEAN COMRANY, LIM- ITED, OF LONDON, ENGLAND, A. CORPORATION OF GREAT BRITAIN.

SAFETY CUT-OUT DEVICE FOR USE ON GAS'EEUIE'PLY SYSTEMS.

Application filed September 15, 1921. Serial No. 500,865.

To all whom it may concern:

Be it known that we, GEORGE KEITH and JOHN EDW RD PoiN'roN, both subjects of the King of the United Kingdom of Great Britain and Ireland, and residing at London,

England, and Peterborough, county of Northants, England, respectively, have invented a certain new and useful Improvement in Safety Cut-Out Devices for Use on Gas- Supply Systems, of which the following is a specification.

This invention relates to improvements in that type of safety cut-out device for use on gas supply systems which is normally held open by gas pressure acting on the under side of a.diaphragm valve against the ac tion of a spring but hen closed can only be re-opened on actuation of a manually operable lifting device. E

An important function of such a cut-out device is to prevent the accidental filling of gas-fired biscuit and bread ovens or the like with an explosive mixture of gas and air and thus to obviate the risk of accident by ignition of such an explosive mixture.

Characteristic of the present invention is the feature that the lifting device is so contrived as to be effective in lifting the valve off its seat butto be inoperative in the opposite direction so that the diaphragm cannot be pressed on its seat and thus be liable to be damaged by rough treatment.

In the accompanying drawings Fig. 1 is a vertical section ofa safety cut-out device according to the invention. Fig. 2 is an inverted plan of the lower half of the valve casing. Fig.3 shows a detail hereinafter referred to.

Referring to the drawings, A denotes a diaphragm, preferably of thin metal, held in a diaphragm casing, the diaphragm itself forming a valve which closes on to a central seat 13 of small area compared with the area of the diaphragm. The diaphragm is urged towards its seat by a spring D acting on a plunger C movable in the upper half of the diaphragm casing and adapted to rest on said diaphragm. For lifting the diaphragm off its seat there is provided a spindle E having a head F engageable with the plunger C and operative tolift the plunger upwards but inoperative to press it downwards. The

upper end of the spindle Eis fitted with a washer G retained in place by a split pin passing through the spindle. H denotes a bush adjustable to regulate the compression of the spring D, said bush being split transversely and sprung so that it is not'liable to change its position in the diaphragm casing in consequence of vibration. In Fig. 3 is shown a pronged key J for effecting the adjustment of the bush, the prongs of which key are adapted to pass through holes in the washer G.

The operation of the device is as follows Gas is admitted to the centre of the valve seat B by way of either of the inlets K and L whichever is more convenient So long as the diaphragm is held on to its seat the high pressure within the range of operation of the apparatus is unableto lift the diaphragm due to the small area against which the is pressing. If, however, the diaphragm be lifted off its seat by manual operation of the spindle E, high pressure is established underneath the diaphragm which latter will be held up, permitting the gas to flow to the outlet M, until the pressure has again fallen to a predetermined point. In ordinary usage, for instance, the maximum working pressure is 6 mercury, and the valve is set to close again if by chance-the pressure is reduced below, say, 1 mercury. Even if the pressure he re-established at 6", the valve will not re-open unless by operation of the spindleE, the latter having in effect a one-way connection with the plunger C.

lVe claim A safety cut-out device for use on gas supply systems, comprising a diaphragm valve element, a diaphragm casing across which said diaphragm is stretched. said casing presenting on one side of said diaphragm a central valve seat of small area compared with the area of said diaphragm, a plunger movablein said casing on the other side of said diaphragm, a manually operable spindle also on said other side of said diaphragm and having a head engageable with said plunger and operative to move said plunger away from said diaphragm but inoperative names to this specification in the presence of to move said plunger towards said diatwo subscribing Witnesses. phragm and a spring surrounding said GEORGE KEITH. spindle and pressing said plunger against JOHN EDVARD POINTON. 5 said diaphragm in the direction towards said Witnesses:

seat. KATE FOTHERINGHAM,

In testimony whereof We have signed our ISABEL RoLLo. 

